Investigation into Effect of Rotor RPM on Degree of Separation in Air Classifier

The development and performance optimization of an air classifier is an issue of great challenge and part of emerging nascent technology. Air classification is one of the emerging technological innovation system used in pharmaceutical, construction and powder industries. This technology uses air as a separation media and classifies a product by size, shape of granules and form. It is a dry classification method. Extensive literature survey has been done in this field but commercially available classifiers cannot be used for user specified purposes. The work here showcases all the empirical results obtained from the real time system analysis in various working conditions. The air classifier designed here is used in construction industry to separate the raw crushed sand obtained from mill into usable crushed sand (main product) and fine dust (secondary product). The capacity of the classifier is 5 tons/hour. The work is focused on settling velocity of particles in an air classifier depending upon rotor rpm. Theoretical and experimental studies are carried out to investigate the effect of settling velocities at various rotor rotations in rpm. Theoretical analysis was made to find the results and these results were then validated by experimental analysis. The desired optimum rotation is found out to be 276.7rpm, needed for classification of sand and to separate particles with size less than 2.36mm. The air flow and air velocity trajectory pattern was also studied using CFD analysis. The performance enhancement of air classifier with rotor rpm optimization could be considered as an innovation.